Comments on some macros for FPP

1. Macro for determining the tzero offsets:   tzero_calc.C

•  Create a root tree with the L.fpp variables. Macro assumes the root file is Afile.root .  Can be modified in macro.
• Create file old_tzero.dat . This file is the L.fpp. TOffset array. It will be 24x40 = 960 lines. The database is setup in terms of the 24 FPP planes in the order V1-3,U1-3,V4-6,U4-6,U7-8,V7-8,X1-2,U9-11,V9-11 .
• Run the macro. The macro is set to produce histograms of L.fpp.(pltype)(plnum).ltdc for each wiregroup in that plane with pltype="u","v" or "x" and plnum = 1-11 for "U" and "v" or 1-2 for "x". The front chamber 1 and 2 "v" ("u") planes have 20 (22) wiregroups. The rear chamber 3